JabRef 5.15 · org.jabref.logic.exporter.AtomicFileOutputStream

A file output stream that is similar to the standard FileOutputStream, except that all writes are first redirected to a temporary file. When the stream is closed, the temporary file (atomically) replaces the target file.

In detail, the strategy is to:

Write to a temporary file (with .tmp suffix) in the same directory as the destination file.
Create a backup (with .bak suffix) of the original file (if it exists) in the same directory.
Move the temporary file to the correct place, overwriting any file that already exists at that location.
Delete the backup file (if configured to do so).

If all goes well, no temporary or backup files will remain on disk after closing the stream.

Errors are handled as follows:

If anything goes wrong while writing to the temporary file, the temporary file will be deleted (leaving the original file untouched).
If anything goes wrong while copying the temporary file to the target file, the backup of the original file is kept.

Implementation inspired by code from Marty Lamb and Apache.

Field Summary

Modifier and Type	Field and Description
private final Path	backupFile A backup of the target file (if it exists), created when the stream is closed
private boolean	errorDuringWrite
private final boolean	keepBackup
private static final Logger	LOGGER
private static final String	SAVE_EXTENSION
private final Path	targetFile The file we want to create/replace.
private static final String	TEMPORARY_EXTENSION
private final Path	temporaryFile The file to which writes are redirected to.
private FileLock	temporaryFileLock

Inherited from java.io.FilterOutputStream:: out

Constructor Summary

Access	Constructor and Description
public	AtomicFileOutputStream(Path the path of the file to write to or replace path, boolean whether to keep the backup file (.sav) after a successful write process keepBackup) Creates a new output stream to write to or replace the file at the specified path.
public	AtomicFileOutputStream(Path the path of the file to write to or replace path) Creates a new output stream to write to or replace the file at the specified path.
pack-priv	AtomicFileOutputStream(Path path, Path pathOfTemporaryFile, OutputStream temporaryFileOutputStream, boolean keepBackup) Required for proper testing

Method Summary

Modifier and Type	Method and Description
public void	abort() Closes the write process to the temporary file but does not commit to the target file.
private void	cleanup()
public void	close() Overrides java.io.FilterOutputStream.close. Implements java.io.Closeable.close. perform the final operations to move the temporary file to its final destination
public void	flush() Overrides java.io.FilterOutputStream.flush. Implements java.io.Flushable.flush. Flushes this output stream and forces any buffered output bytes to be written out to the stream.
public Path	getBackup() Returns the path of the backup copy of the original file (may not exist)
private static Path	getPathOfSaveBackupFile(Path targetFile)
private static Path	getPathOfTemporaryFile(Path targetFile)
public void	write(byte[] the data. b, int the start offset in the data. off, int the number of bytes to write. len) Overrides java.io.FilterOutputStream.write. Overridden because of cleanup actions in case of an error
public void	write(int the `byte`. b) Overrides java.io.FilterOutputStream.write. Writes the specified `byte` to this output stream.

Inherited from java.io.FilterOutputStream:: write

Field Detail

backupFile	back to summary
private final Path backupFile A backup of the target file (if it exists), created when the stream is closed

errorDuringWrite	back to summary
private boolean errorDuringWrite

keepBackup	back to summary
private final boolean keepBackup

LOGGER	back to summary
private static final Logger LOGGER

SAVE_EXTENSION	back to summary
private static final String SAVE_EXTENSION

targetFile	back to summary
private final Path targetFile The file we want to create/replace.

TEMPORARY_EXTENSION	back to summary
private static final String TEMPORARY_EXTENSION

temporaryFile	back to summary
private final Path temporaryFile The file to which writes are redirected to.

temporaryFileLock	back to summary
private FileLock temporaryFileLock

Constructor Detail

AtomicFileOutputStream	back to summary
public AtomicFileOutputStream(Path path, boolean keepBackup) throws IOException Creates a new output stream to write to or replace the file at the specified path. Parameters path:Path the path of the file to write to or replace keepBackup:boolean whether to keep the backup file (.sav) after a successful write process

AtomicFileOutputStream

back to summary

public AtomicFileOutputStream(Path path, boolean keepBackup) throws IOException

Creates a new output stream to write to or replace the file at the specified path.

Parameters

path:Path: the path of the file to write to or replace
keepBackup:boolean: whether to keep the backup file (.sav) after a successful write process

AtomicFileOutputStream	back to summary
public AtomicFileOutputStream(Path path) throws IOException Creates a new output stream to write to or replace the file at the specified path. The backup file (.sav) is deleted when write was successful. Parameters path:Path the path of the file to write to or replace

AtomicFileOutputStream

back to summary

public AtomicFileOutputStream(Path path) throws IOException

Creates a new output stream to write to or replace the file at the specified path. The backup file (.sav) is deleted when write was successful.

Parameters

path:Path: the path of the file to write to or replace

AtomicFileOutputStream	back to summary
pack-priv AtomicFileOutputStream(Path path, Path pathOfTemporaryFile, OutputStream temporaryFileOutputStream, boolean keepBackup) throws IOException Required for proper testing

Method Detail

abort	back to summary
public void abort() Closes the write process to the temporary file but does not commit to the target file.

cleanup	back to summary
private void cleanup()

close	back to summary
public void close() throws IOException Overrides java.io.FilterOutputStream.close. Implements java.io.Closeable.close. perform the final operations to move the temporary file to its final destination Annotations @Override Exceptions IOException: Doc from java.io.FilterOutputStream.close. if an I/O error occurs.

back to summary

public void close() throws IOException

Overrides java.io.FilterOutputStream.close.

Implements java.io.Closeable.close.

perform the final operations to move the temporary file to its final destination

Annotations

@Override

Exceptions

IOException:

Doc from java.io.FilterOutputStream.close.

if an I/O error occurs.

flush	back to summary
public void flush() throws IOException Overrides java.io.FilterOutputStream.flush. Implements java.io.Flushable.flush. Doc from java.io.FilterOutputStream.flush. Flushes this output stream and forces any buffered output bytes to be written out to the stream. Annotations @Override Exceptions IOException: if an I/O error occurs.

flush

back to summary

public void flush() throws IOException

Overrides java.io.FilterOutputStream.flush.

Implements java.io.Flushable.flush.

Doc from java.io.FilterOutputStream.flush.

Flushes this output stream and forces any buffered output bytes to be written out to the stream.

Annotations

@Override

Exceptions

IOException:: if an I/O error occurs.

getBackup	back to summary
public Path getBackup() Returns the path of the backup copy of the original file (may not exist)

getPathOfSaveBackupFile	back to summary
private static Path getPathOfSaveBackupFile(Path targetFile)

getPathOfTemporaryFile	back to summary
private static Path getPathOfTemporaryFile(Path targetFile)

write	back to summary
public void write(byte[] b, int off, int len) throws IOException Overrides java.io.FilterOutputStream.write. Overridden because of cleanup actions in case of an error Parameters b:byte[] Doc from java.io.FilterOutputStream.write. the data. off:int Doc from java.io.FilterOutputStream.write. the start offset in the data. len:int Doc from java.io.FilterOutputStream.write. the number of bytes to write. Annotations @Override Exceptions IOException: Doc from java.io.FilterOutputStream.write. if an I/O error occurs.

write

back to summary

public void write(byte[] b, int off, int len) throws IOException

Overrides java.io.FilterOutputStream.write.

Overridden because of cleanup actions in case of an error

Parameters

b:byte[]

Doc from java.io.FilterOutputStream.write.

the data.

off:int

Doc from java.io.FilterOutputStream.write.

the start offset in the data.

len:int

Doc from java.io.FilterOutputStream.write.

the number of bytes to write.

Annotations

@Override

Exceptions

IOException:

Doc from java.io.FilterOutputStream.write.

if an I/O error occurs.

write back to summary

write	back to summary
public void write(int b) throws IOException Overrides java.io.FilterOutputStream.write. Doc from java.io.FilterOutputStream.write. Writes the specified `byte` to this output stream. The `write` method of `FilterOutputStream` calls the `write` method of its underlying output stream, that is, it performs `out.write(b)`. Implements the abstract `write` method of `OutputStream`. Parameters b:int the `byte`. Annotations @Override Exceptions IOException: if an I/O error occurs.

public void write(int b) throws IOException

Overrides java.io.FilterOutputStream.write.

Doc from java.io.FilterOutputStream.write.

Writes the specified byte to this output stream.

The write method of FilterOutputStream calls the write method of its underlying output stream, that is, it performs out.write(b).

Implements the abstract write method of OutputStream.

Parameters

b:int: the byte.

Annotations

@Override

Exceptions

IOException:: if an I/O error occurs.

public Class AtomicFileOutputStream

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail